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# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
minus=-
# standard input
fd=0
exec 3<&$fd
read line <&3
echo from stdin: $line
# close fd 3
exec 3<&${minus}
# should give `bad fd', but exact error messages vary
# read line <&3
# standard output
fd=1
exec 4>&$fd
echo to stdout >&4
exec 4>&$minus
# should give `bad fd', but exact error messages vary
# echo to stdout >&4
unset fd
# these are ambiguous redirects
exec 3<&$fd
exec 4>&$fd
exec 3>&1 4>&2
exec >&${TMPDIR}/err-and-out
echo to stdout
echo to stderr >&2
exec 1>&3 2>&4
echo err-and-out:
cat ${TMPDIR}/err-and-out
rm ${TMPDIR}/err-and-out
fd=${TMPDIR}/err-and-out
exec >&$fd
echo to stdout
echo to stderr >&2
exec 1>&3 2>&4
echo err-and-out:
cat ${TMPDIR}/err-and-out
rm ${TMPDIR}/err-and-out
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